Discrimination device, discrimination method, and program recording medium

ABSTRACT

A discrimination device includes: a log acquisition unit that acquires sensor data including acceleration acquired by a sensor placed in a shoe, a storage unit that stores log data of the sensor data, a log calling unit that calls the log data stored in the storage unit, a discrimination unit that distinguishes a walking state from a waveform of the log data, a threshold setting unit that retains a first threshold and a second threshold, and sets the first threshold and the second threshold based on a discrimination result, and a transmission unit that transmits the discrimination result. When acceleration in the log data has not exceeded the second threshold within a discrimination time, the discrimination device outputs a discrimination result of being erroneous activation, and updates the first threshold based on a value of the acceleration in the traveling direction in the log data according to the discrimination result.

TECHNICAL FIELD

The present invention relates to a discrimination device, adiscrimination method, and a program for distinguishing a walking state.

BACKGROUND ART

In response to growing interest in healthcare for physical conditionmanagement, a technique has been developed for measuring walking usingsensor data acquired by a sensor attached to a body. In order to stablyuse the walking measurement for a long time, power saving of a sensorthat acquires sensor data and a measurement device that performs walkingmeasurement using the sensor data is required.

PTL 1 discloses a walking-linked communication device that performscommunication in conjunction with walking of a user. The device of PTL 1includes a pressure sensing unit that detects a foot pressure of theuser during walking or running, a communication unit that transmitsdata, and a control unit that controls the pressure sensing unit and thecommunication unit. The control unit of the device of PTL 1 monitorsoutput of the pressure sensing unit and controls on and off oftransmission of data by the communication unit according to therelationship between the output and a threshold.

CITATION LIST Patent Literature [PTL 1] JP 2017-217213 A SUMMARY OFINVENTION Technical Problem

According to the method of PTL 1, power consumption at the time oftransmission of data by the communication unit can be suppressed.However, in the method of PTL 1, because the threshold set for output ofthe pressure sensing unit is fixed, there is a problem that it isdifficult to cope with a change when the use environment of the userchanges. For example, the device of PTL 1 may not be activated or may beerroneously activated depending on setting of the threshold. The methodof PTL 1 has a problem that, due to a change in the walking state, thethreshold is too high and measurement efficiency deteriorates, or thethreshold is too low and the power is excessively consumed.

An object of the present invention is to solve the above-describedproblems, and to provide a discrimination device that achieves highefficiency and low power consumption of walking measurement whileflexibly responding to changes in a walking state.

Solution to Problem

A discrimination device according to one aspect of the present inventionincludes a log acquisition unit that acquires sensor data includingacceleration acquired by a sensor placed in a shoe, a storage unit thatstories log data of the sensor data acquired by the log acquisitionunit, a log calling unit that calls the log data stored in the storageunit, a discrimination unit that distinguishes a walking state from awaveform of the log data called by the log calling unit, a thresholdsetting unit that retains a first threshold related to acceleration in agravity direction and a second threshold related to acceleration in atraveling direction, and sets the first threshold and the secondthreshold based on a discrimination result by the discrimination unit,and a transmission unit that transmits the discrimination result by thediscrimination unit. When acceleration included in the log data has notexceeded the second threshold within a discrimination time, thediscrimination unit outputs a discrimination result that it is erroneousactivation. The threshold setting unit updates the first threshold basedon a value of the acceleration in the traveling direction included inthe log data according to the discrimination result that it is erroneousactivation.

A discrimination method of one aspect of the present invention includesacquiring sensor data including acceleration acquired by a sensor placedin a shoe, storing log data of the acquired sensor data in a storageunit, calling the log data stored in the storage unit, distinguishing awalking state from a waveform of the called log data, setting a firstthreshold related to acceleration in a gravity direction and a secondthreshold related to acceleration in a traveling direction based on adiscrimination result of the walking state, outputting a discriminationresult that it is erroneous activation when acceleration included in thelog data has not exceeded the second threshold within a discriminationtime, and updating the first threshold based on a value of theacceleration in the traveling direction included in the log dataaccording to the discrimination result that it is erroneous activation.

A program according to one aspect of the present invention causes acomputer to execute processing including acquiring sensor data includingacceleration acquired by a sensor placed in a shoe, storing the log dataof the acquired sensor data in a storage unit, calling the log datastored in the storage unit, distinguishing a walking state from awaveform of the called log data, setting a first threshold related toacceleration in a gravity direction and a second threshold related toacceleration in a traveling direction based on a discrimination resultof the walking state, outputting a discrimination result that it iserroneous activation when acceleration included in the log data has notexceeded the second threshold within a discrimination time, and updatingthe first threshold based on a value of the acceleration in thetraveling direction included in the log data according to thediscrimination result that it is erroneous activation.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a walkingdiscrimination device that achieves high efficiency and low powerconsumption of walking measurement while flexibly responding to changesin a walking state.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a walkingmeasurement system according to a first example embodiment of thepresent invention.

FIG. 2 is a conceptual diagram illustrating an arrangement example of awalking discrimination device of the walking measurement systemaccording to the first example embodiment of the present invention.

FIG. 3 is a conceptual diagram for illustrating a coordinate system ofsensor data acquired by the walking measurement system according to thefirst example embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of a dataacquisition device of the walking measurement system according to thefirst example embodiment of the present invention.

FIG. 5 is a conceptual diagram for illustrating an operation mode of thediscrimination device according to the first example embodiment of thepresent invention.

FIG. 6 is a conceptual diagram for illustrating update of a firstthreshold by the discrimination device according to the first exampleembodiment of the present invention.

FIG. 7 is a flowchart for illustrating initial setting of the firstthreshold by the discrimination device according to the first exampleembodiment of the present invention.

FIG. 8 is a flowchart for illustrating an operation of thediscrimination device according to the first example embodiment of thepresent invention.

FIG. 9 is a flowchart for illustrating a walking discrimination phase bythe discrimination device according to the first example embodiment ofthe present invention.

FIG. 10 is a conceptual diagram illustrating a hardware configurationfor achieving the discrimination device and the walking measurementdevice according to the first example embodiment of the presentinvention.

EXAMPLE EMBODIMENT

Hereinafter, example embodiments of the present invention will bedescribed with reference to the drawings. However, although the exampleembodiments to be described below are technically preferably limited inorder to carry out the present invention, the scope of the invention isnot limited to the following. In all the drawings used in the followingdescription of the example embodiment, the same reference numerals aregiven to similar parts unless there is a particular reason. In thefollowing example embodiments, repeated description of similarconfigurations and operations may be omitted. The directions of arrowsin the drawings illustrate examples, and do not limit the directions ofsignals and processing between blocks.

First Example Embodiment

First, a walking measurement system according to a first exampleembodiment of the present invention will be described with reference tothe drawings. The walking measurement system of the present exampleembodiment calculates an attitude angle using sensor data acquired by anacceleration sensor and an angular velocity sensor arranged on a shoe,and measures walking on the basis of time series data of the attitudeangle. For example, the walking measurement system of the presentexample embodiment calculates the attitude angle using acceleration dataand angular velocity data acquired by an inertial measurement unit (IMU)arranged on a shoe footbed (also referred to as an insole). Whenswitching an operation mode using the sensor data, the walkingmeasurement system of the present example embodiment distinguishes thewalking state using the acceleration data acquired by the accelerationsensor, and performs walking measurement according to the discriminationresult.

(Configuration)

FIG. 1 is a block diagram illustrating an example of a configuration ofa walking measurement system 1 of the present example embodiment. Thewalking measurement system 1 includes a data acquisition device 11, adiscrimination device 12, and a walking measurement device 13. The dataacquisition device 11 and the discrimination device 12 constitute awalking discrimination device 10. The data acquisition device 11 and thediscrimination device 12 may be connected by wire or wirelessly. Thediscrimination device 12 and the walking measurement device 13 may beconnected by wire or wirelessly. A display device (not illustrated) thatdisplays a discrimination result of the discrimination device 12 and ameasurement result of the walking measurement device 13 may be added tothe walking measurement device 13. When the walking measurement device13 includes a display unit, the discrimination result of thediscrimination device 12 and the measurement result of the walkingmeasurement device 13 may be displayed on the display unit of thewalking measurement device 13.

FIG. 2 is a conceptual diagram illustrating an example in which thewalking discrimination device 10 is installed in the shoe 100. In theexample of FIG. 2, the walking discrimination device 10 is installed ata position corresponding to a back side of an arch of the foot. Theposition where the walking discrimination device 10 is installed may bea position other than the back side of the arch of the foot as long asit is in the shoe or on a surface of the shoe. For example, the walkingdiscrimination device 10 is installed on an insole inserted into theshoe 100. The walking discrimination device 10 may be installed infootwear other than shoes, socks, or the like as long as a walking statecan be detected.

The data acquisition device 11 is connected to the discrimination device12. The data acquisition device 11 includes at least an accelerationsensor and an angular velocity sensor. The data acquisition device 11converts data acquired by the acceleration sensor and the angularvelocity sensor into digital data (also referred to as sensor data), andtransmits the sensor data after the conversion to the discriminationdevice 12. The data acquisition device 11 and the walking measurementdevice 13 may be configured to be directly connected without interposingthe discrimination device 12 therebetween.

FIG. 3 is a conceptual diagram for illustrating a coordinate system ofsensor data acquired by the data acquisition device 11. In the exampleof FIG. 3, a lateral direction of a walker is set to an X-axis direction(rightward direction is positive), a traveling direction of the walkeris set to a Y-axis direction (forward direction is positive), and agravity direction is set to a Z-axis direction (vertically upwarddirection is positive).

The data acquisition device 11 is achieved by, for example, an inertialmeasurement device including an acceleration sensor and an angularvelocity sensor. An example of the inertial measurement device is theIMU. The IMU includes a three-axis acceleration sensor and an angularvelocity sensor. An example of the inertial measurement device is avertical gyro (VG). The VG has a configuration similar to that of theIMU, and can output a roll angle and a pitch angle with reference to thegravity direction by a method called strapdown. An example of theinertial measurement device is an attitude heading reference system(AHRS). The AHRS has a configuration in which an electronic compass isadded to the VG. The AHRS can output a yaw angle in addition to the rollangle and the pitch angle. As an example of the inertial measurementdevice, there is a global positioning system/inertial navigation system(GPS/INS). The GPS/INS has a configuration in which the GPS is added tothe AHRS. The GPS/INS can calculate a position in a three-dimensionalspace in addition to an attitude angle (roll angle, pitch angle, and yawangle), the position can be estimated with high accuracy.

When the acceleration data is used, the attitude angle can be calculatedfrom the magnitude of acceleration applied in the axial direction ofeach of the pitch axis and the roll axis. When the angular velocity datais used, values of the angular velocity with each of the pitch axis, theroll axis, and the yaw axis as central axes can be integrated, tothereby calculate the attitude angle around each of these axes.Meanwhile, high frequency noise changing in various directions isincluded in the acceleration data, and low frequency noise in the samedirection is always included in the angular velocity data. Thus, byapplying a low-pass filter to the acceleration data to remove ahigh-frequency component, applying a high-pass filter to the angularvelocity data to remove a low-frequency component, and combining outputsthereof, accuracy of sensor data from a foot portion in which noise iseasily mixed is improved. It is also possible to improve accuracy of thesensor data by applying a complementary filter to each of theacceleration data and the angular velocity data and taking a weightedaverage.

The discrimination device 12 is connected to the data acquisition device11 and the walking measurement device 13. The discrimination device 12acquires sensor data from the data acquisition device 11. For example,the discrimination device 12 is achieved by a microcomputer.

The discrimination device 12 switches the operation mode of the walkingmeasurement system 1 according to a value of the acceleration dataincluded in the sensor data from the data acquisition device 11. Thewalking measurement system 1 operates in at least two operation modesincluding a power saving mode and a normal mode. The power saving modeis a mode in which the discrimination device 12 operates and the walkingmeasurement device 13 stops. The normal mode is a mode in which thediscrimination device 12 operates in a walking discrimination phase andthe walking measurement device 13 operates normally. For example, inorder to reduce the power consumption of the walking discriminationdevice 10, the discrimination device 12 may be configured such that anacquisition frequency and a discrimination frequency of data are reducedin the power saving mode, and the acquisition frequency and thediscrimination frequency of data are increased in the walkingdiscrimination phase of the normal mode.

The discrimination device 12 switches the operation mode using twothresholds. A first threshold of the two thresholds is a threshold setfor acceleration in the gravity direction (Z direction in FIG. 3) whenthe operation mode is switched from the power saving mode to the normalmode. A second threshold of the two thresholds is a threshold set foracceleration in the traveling direction (Y direction in FIG. 3) duringthe walking discrimination phase for several seconds after switchingfrom the operation mode to the normal mode.

When the acceleration in the gravity direction (Z direction in FIG. 3)exceeds the first threshold, the discrimination device 12 switches fromthe power saving mode to the normal mode. When switching from the powersaving mode to the normal mode, the discrimination device 12 transmitsthe sensor data to the walking measurement device 13. The walkingmeasurement device 13 that has received the sensor data from thediscrimination device 12 shifts to the normal mode with the sensor dataas a trigger. When switching from the power saving mode to the normalmode, a trigger signal may be transmitted from the discrimination device12 to the walking measurement device 13, and the walking measurementdevice 13 responding to the trigger signal may be configured to directlyreceive the sensor signal from the data acquisition device 11.

The discrimination device 12 verifies whether the acceleration in thetraveling direction exceeds the second threshold using log data(hereinafter also referred to as a log) of the sensor data in thewalking discrimination phase immediately after switching to the normalmode. The discrimination device 12 distinguishes whether it is stablewalking, stop of walking, or erroneous activation according to averification result of whether the acceleration in the travelingdirection exceeds the second threshold.

When the discrimination device 12 distinguishes that it is stablewalking, the discrimination device 12 continues transmitting the sensordata to the walking discrimination device 10. By continuing thetransmission of the sensor data from the discrimination device 12 to thewalking measurement device 13, the walking measurement by the walkingmeasurement device 13 is performed in the normal mode. When the walkingmeasurement device 13 is configured to directly receive the sensorsignal from the data acquisition device 11, it is only required totransmit a trigger signal indicating a discrimination result that it isstable walking from the discrimination device 12 to the walkingmeasurement device 13. In that case, the walking measurement by thewalking measurement device 13 is continued according to the triggersignal. The walking measurement by the walking measurement device 13 maybe configured to be continued unless the trigger signal is received fromthe discrimination device 12.

When the discrimination device 12 distinguishes that walking is stopped,the discrimination device 12 stops transmitting the sensor data to thewalking measurement device 13. By stopping the transmission of thesensor data from the discrimination device 12 to the walking measurementdevice 13, the walking measurement by the walking measurement device 13is stopped. When the walking measurement device 13 is configured todirectly receive the sensor signal from the data acquisition device 11,it is only required to transmit a trigger signal indicating adiscrimination result that walking is stopped from the discriminationdevice 12 to the walking measurement device 13. In that case, thewalking measurement by the walking measurement device 13 is stoppedaccording to the trigger signal.

When the discrimination device 12 distinguishes that it is erroneousactivation, the discrimination device 12 updates the first threshold onthe basis of a maximum value of the acceleration in the travelingdirection (Y direction in FIG. 3), and the transmission of the sensordata to the walking measurement device 13 is stopped. By stopping thetransmission of the sensor data from the discrimination device 12 to thewalking measurement device 13, the walking measurement by the walkingmeasurement device 13 is stopped. If the first threshold is updated toan excessively large value, there is a possibility that thediscrimination device 12 will not be activated thereafter. Therefore,when the discrimination device 12 is not activated even once under acertain condition (for example, several hours), the value of the firstthreshold is returned to a value at the time of a previous normalactivation. When the walking measurement device 13 is configured todirectly receive the sensor signal from the data acquisition device 11,it is only required to transmit a signal indicating a discriminationresult that it is erroneous activation from the discrimination device 12to the walking measurement device 13. In that case, the walkingmeasurement by the walking measurement device 13 is stopped in responseto the signal indicating the discrimination result that it is erroneousactivation.

The walking measurement device 13 receives sensor data from the dataacquisition device 11 via the discrimination device 12. The walkingmeasurement device 13 executes the walking measurement using thereceived sensor data. Note that in the present example embodiment, theconfiguration and operation of the walking measurement device 13 are notparticularly limited as long as the walking measurement is executedusing the sensor data. The walking measurement device 13 may beconfigured to directly receive the sensor signal from the dataacquisition device 11 according to the trigger signal output when thediscrimination device 12 shifts to the normal mode.

For example, the walking measurement device 13 calculates the attitudeangle using the received sensor data. In the present example embodiment,the attitude angle is an angle of the sole surface with respect to ahorizontal plane (ground). The walking measurement device 13 generatestime series data of the attitude angle. The walking measurement device13 generates the time series data of the attitude angle at apredetermined timing or a predetermined time interval set in accordancewith a general walking cycle or a walking cycle unique to the user. Thewalking measurement device 13 executes walking measurement using thetime series data of the attitude angle. The walking measurement device13 outputs an analysis of a walking phase and measurement results of astride, a walking speed, a sensor height, and the like to a displaydevice that is not illustrated or another system.

The walking measurement device 13 acquires a discrimination result bythe discrimination device 12. The walking measurement device 13continues or stops the walking measurement on the basis of thediscrimination result from the discrimination device 12. For example,the walking measurement device 13 continues to generate the time seriesdata of the attitude angle in a period in which walking of the user iscontinued (stable walking period). The walking measurement device 13performs the walking measurement using the generated time series data.The timing of generating the time series data of the attitude angle andcontents of the walking measurement can be freely set.

For example, the walking measurement device 13 is achieved by software(application) or a circuit installed in a portable terminal device suchas a smartphone, a mobile phone, a tablet, or a laptop personalcomputer. When the walking measurement device 13 is used for dataanalysis in research or the like, for example, the walking measurementdevice 13 may be achieved by software or a circuit installed in aninformation processing device such as a stationary computer or a server.

The configuration of the walking measurement system 1 has been describedabove. Note that the configuration of the walking measurement system 1of FIG. 1 is an example, and the configuration of the walkingmeasurement system 1 of the present example embodiment is not limited tothe mode as it is.

[Assessment Device]

Next, a configuration of the discrimination device 12 will be describedwith reference to the drawings. As illustrated in FIG. 1, thediscrimination device 12 includes a log acquisition unit 121, a storageunit 122, a log calling unit 123, a discrimination unit 125, a thresholdsetting unit 126, and a transmission unit 127. For example, thecomponents of the discrimination device 12 may be achieved by amicrocomputer having a dedicated circuit, or may be achieved by softwaremounted on the microcomputer.

The log acquisition unit 121 is connected to the data acquisition device11, the storage unit 122, and the log calling unit 123. The logacquisition unit 121 receives the log data of the sensor data from thedata acquisition device 11. The log acquisition unit 121 stores thereceived log data in the storage unit 122. The log acquisition unit 121outputs a call instruction for the log data to the log calling unit 123.For example, every time the log data is acquired, the log acquisitionunit 121 outputs the call instruction for the log data to the logcalling unit 123. For example, the log acquisition unit 121 outputs thecall instruction for the log data to the log calling unit 123 when apredetermined time elapses after acquisition of the log data. The timingat which the log acquisition unit 121 outputs the call instruction forthe log data to the log calling unit 123 can be freely set. When the logcalling unit 123 is configured to control the call for the log data, itis only required to configure the log acquisition unit 121 not toperform the call instruction for the log data to the log calling unit123.

The storage unit 122 is connected to the log acquisition unit 121 andthe log calling unit 123. In the storage unit 122, the log data of thesensor data is stored by the log acquisition unit 121. The storage unit122 receives an access by the log calling unit 123, and the log data ofthe sensor data stored in itself is read by the log calling unit 123.

The log calling unit 123 is connected to the log acquisition unit 121,the storage unit 122, and the discrimination unit 125. The log callingunit 123 reads the log data of the sensor data from the storage unit 122in response to the call instruction for the log from the log acquisitionunit 121. The log calling unit 123 outputs the called log data to thediscrimination unit 125. When the log calling unit 123 is configured tocontrol the call for the log data, it is only required to set a timingat which the log data is called in the log calling unit 123. In thiscase, it is only required to configure the log calling unit 123 to readthe log data at a predetermined timing set in advance or atpredetermined time intervals.

The discrimination unit 125 is connected to the log calling unit 123,the threshold setting unit 126, and the transmission unit 127. Thediscrimination unit 125 acquires the log data of the sensor data fromthe log calling unit 123. The discrimination unit 125 switches theoperation mode using two thresholds. A first threshold of the twothresholds is a threshold set for acceleration in the gravity direction(Z direction in FIG. 3) when it is switched from the power saving modeto the normal mode. A second threshold of the two thresholds is athreshold set for acceleration in the traveling direction (Y directionin FIG. 3) in the walking discrimination phase for several seconds afterswitching from the power saving mode to the normal mode.

If the acceleration in the gravity direction exceeds the firstthreshold, the discrimination unit 125 switches the operation mode fromthe power saving mode to the normal mode. After switching the operationmode to the normal mode, the discrimination unit 125 verifies whetherthe acceleration in the traveling direction exceeds the second thresholdusing the log data of the sensor data, thereby distinguishing whether itis stable walking, stop of walking, or erroneous activation.

When the acceleration in the traveling direction has exceeded the secondthreshold in a period until a predetermined discrimination time elapses,the discrimination unit 125 verifies whether the acceleration in thetraveling direction has exceeded the second threshold by a prescribednumber of times or more in the period until the discrimination timeelapses. For example, the discrimination time is set to an elapsed time(about five seconds) of about several steps in general walking. Forexample, the prescribed number of times is set in accordance with thenumber of steps in an elapsed time of about several steps in generalwalking. When the elapsed time is set to five seconds and it isestimated that it is stable walking if the number of steps of aboutthree to five steps is measured, it is only required to set theprescribed number of times to about three times. The discrimination timeand the prescribed number of times may be set to initial setting valuesbased on actual measurement values, or may be individually set for eachuser.

When the acceleration in the traveling direction has exceeded the secondthreshold by the prescribed number of times or more in the period untilthe discrimination time elapses, the discrimination unit 125distinguishes that it is stable walking. In this case, thediscrimination unit 125 outputs a discrimination result that it isstable walking to the transmission unit 127. On the other hand, when theacceleration in the traveling direction has not exceeded the secondthreshold by the prescribed number of times or more in the period untilthe discrimination time elapses, the discrimination unit 125distinguishes that walking is stopped. In this case, the discriminationunit 125 outputs a discrimination result that walking is stopped to thetransmission unit 127.

When the acceleration in the traveling direction has not exceeded thesecond threshold in the period until the predetermined discriminationtime elapses, the discrimination unit 125 distinguishes that it iserroneous activation. When the discrimination unit 125 distinguishesthat it is erroneous activation, the discrimination unit 125 outputs adiscrimination result that it is erroneous activation to thetransmission unit and outputs log data of acceleration in the travelingdirection to the threshold setting unit 126.

The threshold setting unit 126 is connected to the discrimination unit125. The threshold setting unit 126 retains the first threshold relatedto the acceleration in the gravity direction (Z direction in FIG. 3) andthe second threshold related to the acceleration in the travelingdirection (Y direction in FIG. 3).

When initially setting the thresholds for the user, the thresholdsetting unit 126 acquires the log data of the acceleration in thetraveling direction from the discrimination unit 125, and calculates amaximum value P0 of the acceleration in the traveling direction. Thethreshold setting unit 126 sets the first threshold and the secondthreshold using the acquired maximum value P0.

For example, the threshold setting unit 126 sets the first threshold Ausing following Equation 1 (where 0<q<1). The first threshold A is athreshold updated on the basis of the acceleration in the travelingdirection (Y direction in FIG. 3) after the initial setting. Forexample, the coefficient q (also referred to as a first coefficient) isset to approximately 0.5. The first threshold A is set to such an extentas to immediately reacts to a light movement. The first threshold A maybe calculated using an equation other than Equation 1 as long as thefirst threshold A is set to such an extent as to immediately react to alight movement.

A=q×P0  (1)

For example, the threshold setting unit 126 sets the second threshold Busing following Equation 2 (where 0<q<s<1). The second threshold B is avalue larger than the first threshold A and is a threshold fixed afterinitial setting. For example, the coefficient s (also referred to as afirst coefficient) is set to approximately 0.6. The second threshold Bis set to be larger than the first threshold A, for example,approximately 2.5 times gravitational acceleration. The second thresholdB may be calculated using an equation other than Equation 2 as long asthe second threshold B is set to be larger than the first threshold A.

B=s×P0  (2)

In the example using Equations 1 and 2, in order to set the secondthreshold B to a larger value than the first threshold A, the firstthreshold A and the second threshold B are set using the same value(maximum value P0 of the acceleration in the traveling direction). Thefirst threshold A and the second threshold B may be set usingacceleration values in different directions as long as the secondthreshold B can be set to a larger value than the first threshold A.

When the acceleration in the traveling direction has not exceeded thesecond threshold in the period until the predetermined discriminationtime elapses, the threshold setting unit 126 acquires a log of theacceleration in the traveling direction from the discrimination unit125. The threshold setting unit 126 performs a state discrimination fromcharacteristics of a waveform of the log data of the acceleration in thetraveling direction, and adjusts the threshold on the basis of thedistinguished state.

When acquiring the log data of the acceleration in the travelingdirection from the discrimination unit 125 in the walking discriminationphase, the threshold setting unit 126 calculates the maximum value ofthe acceleration in the traveling direction. The threshold setting unit126 updates the first threshold on the basis of the calculated maximumvalue. The threshold setting unit 126 outputs the updated firstthreshold to the discrimination unit 125.

The transmission unit 127 is connected to the discrimination unit 125and the walking measurement device 13. The transmission unit 127acquires the discrimination result from the discrimination unit 125. Thetransmission unit 127 transmits the acquired discrimination result tothe walking measurement device 13. For example, when the discriminationresult that it is stable walking is transmitted from the transmissionunit 127 to the walking measurement device 13, the walking measurementby the walking measurement device 13 is continued. When thediscrimination result that walking is stopped or erroneous activation istransmitted from the transmission unit 127 to the walking measurementdevice 13, the walking measurement by the walking measurement device 13is stopped.

The configuration of the discrimination device 12 has been describedabove. Note that the configuration of the discrimination device 12 inFIG. 1 is an example, and the configuration of the discrimination device12 of the present example embodiment is not limited to the mode as itis.

[Data Acquisition Device]

Next, the data acquisition device 11 included in the walking measurementsystem 1 will be described with reference to the drawings. FIG. 4 is ablock diagram illustrating an example of a configuration of the dataacquisition device 11. The data acquisition device 11 includes anacceleration sensor 111, an angular velocity sensor 112, a signalprocessing unit 113, and a data output unit 114. The acceleration sensor111 and the angular velocity sensor 112 constitute a sensor 110. Forexample, the data acquisition device 11 is implemented by an IMU.

The acceleration sensor 111 is a sensor that measures acceleration inthree axial directions. The acceleration sensor 111 outputs the measuredacceleration to the signal processing unit 113.

The angular velocity sensor 112 is a sensor that measures an angularvelocity. The angular velocity sensor 112 outputs the measured angularvelocity to the signal processing unit 113.

The signal processing unit 113 acquires each of the acceleration and theangular velocity from each of the acceleration sensor 111 and theangular velocity sensor 112. The signal processing unit 113 converts theacquired acceleration and angular velocity into digital data, andoutputs the digital data (sensor data) after conversion to the dataoutput unit 114. The sensor data includes at least acceleration dataobtained by converting acceleration of analog data into digital data andangular velocity data obtained by converting angular velocity of analogdata into digital data. The sensor data may include an acquisition timeof raw data of acceleration and angular velocity. The signal processingunit may be configured to output sensor data obtained by performingcorrection such as a mounting error, a temperature correction, and alinearity correction on the acquired raw data of the acceleration andthe angular velocity.

The data output unit 114 acquires the sensor data from the signalprocessing unit 113. The data output unit 114 transmits the acquiredsensor data to the discrimination device 12. The data output unit 114may transmit the sensor data to the discrimination device 12 via a wiresuch as a cable or a conductive wire, or may transmit the sensor data tothe discrimination device 12 via wireless communication. For example,the data output unit 114 can be configured to transmit sensor data tothe discrimination device 12 via a wireless communication function (notillustrated) conforming to a standard such as Bluetooth (registeredtrademark) or WiFi (registered trademark). When the sensor data isdirectly transmitted from the data output unit 114 to the walkingmeasurement device 13, it is only required to transmit the sensor datafrom the data output unit 114 to the walking measurement device 13 bywired communication or wireless communication.

The example of the configuration of the data acquisition device 11 hasbeen described above. Note that the configuration of FIG. 4 is anexample, and the configuration of the data acquisition device 11included in the walking measurement system 1 of the present exampleembodiment is not limited to the mode as it is.

[Operation Mode]

Next, switching of the operation mode by the discrimination device 12will be described with reference to the drawings. FIG. 5 is a conceptualdiagram for illustrating an example of switching of the operation modeby the discrimination device 12. In the example of FIG. 5, an example isillustrated in which the mode is switched to a normal mode (B) when thediscrimination device 12 operating in a power saving mode (A) detectsthat the acceleration in the gravity direction (Z direction in FIG. 3)has exceeded the first threshold.

At the initial stage of switching to the normal mode (B) (walkingdiscrimination phase), the discrimination device 12 verifies whether theacceleration in the traveling direction (Y direction in FIG. 3) exceedsthe second threshold. When the acceleration in the traveling directionhas exceeded the second threshold by the prescribed number of times ormore within the discrimination time, the discrimination device 12transmits a discrimination result that it is stable walking to thewalking measurement device 13. When the acceleration in the travelingdirection has exceeded the second threshold within the discriminationtime but has not exceeded the second threshold by the prescribed numberof times or more, the discrimination device 12 transmits adiscrimination result that walking is stopped to the walking measurementdevice 13.

The example of FIG. 5 is an example in which the acceleration in thetraveling direction has not exceeded the second threshold within thediscrimination time. In this case, the discrimination device 12transmits a discrimination result that it is erroneous activation to thewalking measurement device 13 and updates the first threshold.

[Update of First Threshold]

Next, update of the first threshold by the threshold setting unit 126 ofthe discrimination device 12 will be described with reference to thedrawings. FIG. 6 is a conceptual diagram for illustrating an example ofupdate of the first threshold by the threshold setting unit 126. In theexample of FIG. 6, a situation is illustrated in which a waveform of thelog data of the acceleration in the traveling direction (Y direction inFIG. 3) is recorded (C), a maximum value Mn is calculated from thewaveform (D), and the first threshold A is updated to a first thresholdAc on the basis of the calculated maximum value Mn (E).

When acquiring the log data of the acceleration in the travelingdirection from the discrimination unit 125, the threshold setting unit126 calculates the maximum value Mn of the acceleration in the travelingdirection. The threshold setting unit 126 updates the first threshold onthe basis of the calculated maximum value Mn.

For example, the threshold setting unit 126 updates the first thresholdA to the first threshold Ac using following Equation 3. In followingEquation 3, the maximum value of the acceleration in the travelingdirection is described as Mn, a correction coefficient for updating thefirst threshold is described as r, and the first threshold after updateis described as Ac.

Ac=r×Mn  (3)

For example, the correction coefficient r is set to approximately 1.05to 1.1 in order to increase the first threshold by approximately 5% to10%. If the correction coefficient r is too small, erroneous activationis not efficiently suppressed and frequently occurs. If the correctioncoefficient r is too large, the operation mode no longer shifts to thenormal mode. Thus, the correction coefficient r is set to an appropriatevalue that is not too small and not too large. The correctioncoefficient r may be set to an initial setting value based on the actualmeasurement value, or may be individually set for each user.

(Operation)

Next, an operation of the walking measurement system 1 of the presentexample embodiment will be described with reference to the drawings.Hereinafter, description will be started from an example in which thefirst threshold is initially set for the user. Then, a series ofoperations will be described in which the walking measurement system 1detects a start of walking in the low-load power saving mode usingacceleration, and performs walking discrimination when switching to thenormal mode in which walking measurement is performed using theacceleration and angular velocity.

[Initial Setting]

FIG. 7 is a flowchart for illustrating an operation in which the walkingmeasurement system 1 initially sets the first threshold A for the userusing an initial value (first threshold A0) of the first threshold. Forexample, the first threshold A0 is set at the time of production orfactory shipment of the walking discrimination device 10. In the exampleof FIG. 7, it is assumed that an instruction can be issued from thewalking measurement system 1 to the user via a display device, a sounddevice, or the like that is not illustrated. For example, when anapplication having the function of the walking measurement device 13 isinstalled in a terminal device such as a smartphone, an instruction canbe issued via a display device, a voice device, or the like mounted onthe terminal device. In the description along the flowchart of FIG. 7,the walking measurement system 1 will be described as the main body ofoperation.

In FIG. 7, first, when an initial setting operation is performed by theuser, the walking measurement system 1 acquires an initial value (firstthreshold A0) of the first threshold (step S101). For example, the firstthreshold A0 is stored in a storage area (not illustrated) of thediscrimination device 12 or the walking measurement device 13. Theinitial setting operation by the user is an operation performed when theuser uses the walking measurement system 1 for the first time or whenthe first threshold is reset.

Next, the walking measurement system 1 instructs the user to perform anaction in which the acceleration in the gravity direction (Z directionin FIG. 3) exceeds the first threshold A0 (step S102). For example, thewalking measurement system 1 outputs, from the walking measurementdevice 13, display information and voice information for the user toperform an action in which the acceleration in the gravity directionexceeds the first threshold A0.

Here, when the acceleration in the gravity direction has exceeded thefirst threshold A0 (Yes in step S103), the walking measurement system 1instructs the user to perform stable walking (step S104). For example,the walking measurement system 1 outputs display information and voiceinformation for the user to perform stable walking from the walkingmeasurement device 13. On the other hand, when the acceleration in thegravity direction has not exceeded the first threshold A0 (No in stepS103), the processing returns to step S102.

Next, the walking measurement system 1 acquires a walking waveformobtained by stable walking performed by the user (step S105). At thistime, the walking measurement system 1 acquires a walking waveform ofthe acceleration in the traveling direction (Y direction in FIG. 3).

Next, the walking measurement system 1 sets a first threshold A for theuser on the basis of the acquired peak value of the walking waveform(step S106). The walking measurement system 1 causes the thresholdsetting unit 126 of the discrimination device 12 to store the firstthreshold A.

The operation in which the walking measurement system 1 initializes thefirst threshold A for the user using the first threshold A0 has beendescribed above. Note that the flowchart of FIG. 7 is an example, andthe operation of initial setting of the first threshold A by the walkingmeasurement system 1 of the present example embodiment is not limited tothe procedure as it is.

[Switching of Operation Mode]

FIG. 8 is a flowchart for illustrating an example of switching theoperation mode from the power saving mode to the normal mode accordingto an operation of the user. In the description along the flowchart ofFIG. 8, the discrimination device 12 will be described as the main bodyof operation.

In FIG. 8, first, the discrimination device 12 measures acceleration inthe power saving mode (step S111).

When the acceleration in the gravity direction (Z direction in FIG. 3)exceeds the first threshold A under a certain condition (Yes in stepS112), the discrimination device 12 switches the operation mode to thenormal mode (step S113).

On the other hand, when the acceleration in the gravity direction hasnot exceeded the first threshold A under the certain condition (No instep S112), the discrimination device 12 decreases the value of thefirst threshold A (step S114). After step S114, the processing returnsto step S112. For example, in step S114, the value of the firstthreshold A is returned to the value at the time of the previous normalactivation. In step S114, the value of the first threshold A may bedecreased by a predetermined value.

After step S113, the discrimination device 12 shifts to the walkingdiscrimination phase and distinguishes the walking state (step S115). Inthe walking discrimination phase (step S115), the discrimination device12 distinguishes whether the walking state of the user is stablewalking, stop of walking, or erroneous activation.

When the discrimination result is stable walking (Yes in step S116), thediscrimination device 12 outputs an instruction to continue the normalmode to the walking measurement device 13 (step S117). In step S117, thewalking discrimination phase of FIG. 8 ends. The walking discriminationphase in FIG. 8 may be stopped at a stage when the power saving mode isswitched to the normal mode, may be periodically executed, or may becontinued as it is. On the other hand, when the discrimination result isnot stable walking (No in step S116), the discrimination device 12executes different processing depending on whether it is erroneousactivation (step S118).

When it is erroneous activation (Yes in step S118), the discriminationdevice 12 increases the value of the first threshold A (step S119).After step S119, the processing returns to step S112. On the other hand,when it is not erroneous activation (No in step S118), thediscrimination device 12 returns to step S112 without updating the valueof the first threshold A. After step S118 or step S119, the walkingmeasurement device 13 may be configured to be notified of stop walkingor erroneous activation. When the walking measurement device 13 isnotified of stop of walking or erroneous activation, it is only requiredto transmit an instruction to stop the normal mode to the walkingmeasurement device 13.

The example of switching the operation mode from the power saving modeto the normal mode according to the operation of the user has beendescribed above. Note that the flowchart of FIG. 8 is an example, andthe switching of the operation mode from the power saving mode to thenormal mode by the discrimination device 12 of the present exampleembodiment is not limited to the procedure as it is.

[Walking Discrimination Phase]

FIG. 9 is a flowchart for illustrating an operation in the walkingdiscrimination phase executed when the operation mode is switched fromthe power saving mode to the normal mode. In the description along theflowchart of FIG. 9, the discrimination device 12 will be described asthe main body of operation.

In FIG. 9, first, the discrimination device 12 distinguishes whether theacceleration in the traveling direction (Y direction in FIG. 3) hasexceeded the second threshold B within a discrimination time H (stepS121).

When the acceleration in the traveling direction has not exceeded thesecond threshold B within the discrimination time H (No in step S121),the discrimination device 12 distinguishes that it is erroneousactivation (step S122), and records the waveform of the acceleration inthe traveling direction (step S123). Next, the discrimination device 12calculates the maximum value Mn of the waveform of the acceleration inthe traveling direction (step S124). Then, the discrimination device 12resets the first threshold Ac by applying the calculated maximum valueMn to above Equation 3 (step S125). After step S125, the processingproceeds to step S116 in FIG. 8.

On the other hand, when the acceleration in the traveling direction hasexceeded the second threshold B within the discrimination time H (Yes instep S121), the discrimination device 12 distinguishes whether theacceleration in the traveling direction has exceeded the secondthreshold B by a prescribed number of times or more within thediscrimination time H (step S126).

When the acceleration in the traveling direction has exceeded the secondthreshold B by the prescribed number of times or more within thediscrimination time H (Yes in step S126), the discrimination device 12distinguishes that it is stable walking (step S127). On the other hand,when the acceleration in the traveling direction has not exceeded thesecond threshold B by the prescribed number of times or more within thediscrimination time H (No in step S126), the discrimination device 12distinguishes that walking is stopped (step S128). After steps S127 andS128, the processing proceeds to step S116 in FIG. 8.

The operation in the walking discrimination phase has been describedabove. Note that the processing along the flowchart of FIG. 9 is anexample, and the operation in the walking discrimination phase by thediscrimination device 12 is not limited to the procedure as it is.

As described above, the walking measurement system of the presentexample embodiment includes a data acquisition device, a discriminationdevice, and a walking measurement device. The data acquisition deviceaccording to one aspect of the present example embodiment is placed in ashoe, detects acceleration and angular velocity, generates sensor dataincluding the detected acceleration and angular velocity, and transmitsthe generated sensor data to the discrimination device. The walkingmeasurement device according to one aspect of the present exampleembodiment acquires the sensor data generated by the data acquisitiondevice and a discrimination result from the discrimination device, isactivated and stopped according to the discrimination result, andmeasures walking using the sensor data.

The discrimination device according to one aspect of the present exampleembodiment includes a log acquisition unit, a storage unit, a call unit,a discrimination unit, a threshold setting unit, and a transmissionunit. The log acquisition unit acquires sensor data includingacceleration acquired by a sensor placed in a shoe. The storage unitstores log data of the sensor data acquired by the log acquisition unit.The log calling unit calls the log data stored in the storage unit. Thediscrimination unit distinguishes a walking state from a waveform of thelog data called by the log calling unit. When acceleration included inthe log data has not exceeded a second threshold within a discriminationtime, the discrimination unit outputs a discrimination result that it iserroneous activation. The threshold setting unit retains a firstthreshold related to acceleration in a gravity direction and the secondthreshold related to acceleration in a traveling direction, and sets thefirst threshold and the second threshold on the basis of adiscrimination result by the discrimination unit. The threshold settingunit updates the first threshold based on a value of the acceleration inthe traveling direction included in the log data according to thediscrimination result that it is erroneous activation. The transmissionunit transmits the discrimination result by the discrimination unit.

In one aspect of the present example embodiment, the threshold settingunit sets, as the first threshold, a value obtained by multiplying amaximum value of the acceleration in the traveling direction included inthe log data by a correction coefficient according to the discriminationresult that it is erroneous activation.

In one aspect of the present example embodiment, when the accelerationincluded in the log data has exceeded the second threshold by aprescribed number of times or more within a discrimination time, thediscrimination unit outputs the discrimination result that it is stablewalking. On the other hand, when the acceleration included in the logdata has not exceeded the second threshold by the prescribed number oftimes or more within the discrimination time, the discrimination unitoutputs a discrimination result that walking is stopped.

In one aspect of the present example embodiment, when the accelerationincluded in the log data has not exceeded the first threshold under acertain condition, the discrimination unit outputs an instruction todecrease the first threshold to the threshold setting unit. Thethreshold setting unit decreases the first threshold in response to theinstruction to decrease the first threshold by the discrimination unit.For example, the threshold setting unit sets, in response to theinstruction to decrease the first threshold by the discrimination unit,the first threshold to a value of the first threshold when it has beenpreviously distinguished that it is stable walking.

In one aspect of the present example embodiment, the threshold settingunit acquires, at a time of initial setting, the log data of the sensordata acquired by the sensor installed in the shoe of the user performingstable walking. The threshold setting unit sets a value obtained bymultiplying a maximum value of the acceleration in the travelingdirection by a first coefficient as the first threshold, and sets avalue obtained by multiplying a second coefficient smaller than thefirst coefficient by the maximum value of the acceleration in thetraveling direction as the second threshold.

The walking measurement system of the present example embodiment canflexibly set the threshold for switching the operation mode on the basisof the log data of the sensor data. In particular, the walkingmeasurement system of the present example embodiment flexibly sets thefirst threshold of the acceleration in the gravity direction on thebasis of the acceleration in the traveling direction. Thus, with thewalking measurement system of the present example embodiment, it ispossible to achieve high efficiency and low power consumption of walkingmeasurement while flexibly responding to changes in a walking state.

(Hardware)

Here, a hardware configuration for executing the processing of thewalking measurement device according to the first example embodiment ofthe present invention will be described using the information processingdevice 90 of FIG. 10 as an example. Note that the information processingdevice 90 in FIG. 10 is a configuration example for executing theprocessing of the walking measurement device of the first exampleembodiment, and does not limit the scope of the present invention.

As illustrated in FIG. 10, the information processing device 90 includesa processor 91, a main storage device 92, an auxiliary storage device93, an input-output interface 95, and a communication interface 96. InFIG. 10, the interface is abbreviated as I/F. The processor 91, the mainstorage device 92, the auxiliary storage device 93, the input-outputinterface 95, and the communication interface 96 are data-communicablyconnected to each other via a bus 99. The processor 91, the main storagedevice 92, the auxiliary storage device 93, and the input-outputinterface 95 are connected to a network such as the Internet or anintranet via the communication interface 96.

The processor 91 develops a program stored in the auxiliary storagedevice 93 or the like in the main storage device 92 and executes thedeveloped program. In the present example embodiment, it is onlyrequired to use a software program installed in the informationprocessing device 90. The processor 91 executes processing by thewalking measurement device according to the present example embodiment.

The main storage device 92 has an area in which a program is developed.The main storage device 92 is only required to be, for example, avolatile memory such as a dynamic random access memory (DRAM). Anonvolatile memory such as a magnetoresistive random access memory(MRAM) may be configured and added as the main storage device 92.

The auxiliary storage device 93 stores various data. The auxiliarystorage device 93 includes a local disk such as a hard disk or a flashmemory. In addition, the main storage device 92 may be configured tostore various data, and the auxiliary storage device 93 may be omitted.

The input-output interface 95 is an interface for connecting theinformation processing device 90 and a peripheral device. Thecommunication interface 96 is an interface for connecting to an externalsystem or device through a network such as the Internet or an intraneton the basis of a standard or a description. The input-output interface95 and the communication interface 96 may be shared as an interfaceconnected to an external device.

An input device such as a keyboard, a mouse, or a touch panel may beconnected to the information processing device 90 as necessary. Theseinput devices are used to input information and settings. When the touchpanel is used as the input device, the display screen of the displaydevice is only required to also serve as the interface of the inputdevice. Data communication between the processor 91 and the input deviceis only required to be mediated by the input-output interface 95.

The information processing device 90 may be provided with a displaydevice for displaying information. When a display device is provided,the information processing device 90 preferably includes a displaycontrol device (not illustrated) for controlling display of the displaydevice. The display device is only required to be connected to theinformation processing device 90 via the input-output interface 95.

The information processing device 90 may be provided with a disk driveas necessary. The disk drive is connected to the bus 99. The disk drivemediates reading of data and/or program from a recording medium, writingof a processing result of the information processing device 90 to therecording medium, and the like between the processor 91 and therecording medium (program recording medium), which is not illustrated.The recording medium can be achieved by, for example, an opticalrecording medium such as a compact disc (CD) or a digital versatile disc(DVD). The recording medium may be achieved by a semiconductor recordingmedium such as a universal serial bus (USB) memory or a secure digital(SD) card, a magnetic recording medium such as a flexible disk, oranother recording medium.

The above is an example of a hardware configuration for enabling thewalking measurement device according to the first example embodiment ofthe present invention. Note that the hardware configuration of FIG. 10is an example of a hardware configuration for executing arithmeticprocessing of the walking measurement device according to the firstexample embodiment, and does not limit the scope of the presentinvention. A program for causing a computer to execute processingrelated to the walking measurement device according to the first exampleembodiment is also included in the scope of the present invention.Further, a program recording medium in which the program according tothe first example embodiment is recorded is also included in the scopeof the present invention.

The components of the walking measurement device of the first exampleembodiment can be freely combined. The components of the walkingmeasurement device of the first example embodiment may be achieved bysoftware or may be achieved by a circuit.

While the present invention has been particularly shown and describedwith reference to example embodiments thereof, the invention is notlimited to these embodiments. It will be understood by those of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinvention as defined by the claims.

REFERENCE SIGNS LIST

-   1 Walking measurement system-   10 Walking discrimination device-   11 Data acquisition device-   12 Discrimination device-   13 Walking measurement device-   110 Sensor-   111 Acceleration sensor-   112 Angular velocity sensor-   113 Signal processing unit-   114 Data output unit-   121 Log acquisition unit-   122 Storage unit-   123 Log calling unit-   125 Discrimination unit-   126 Threshold setting unit-   127 Transmission unit

What is claimed is:
 1. A discrimination device comprising: at least onememory storing instructions; and at least one processor connected to theat least one memory and configured to execute the instructions to:acquire sensor data including acceleration acquired by a sensor placedin a shoe; store log data of the sensor data that has been acquired in astorage; call the log data stored in the storage; distinguish a walkingstate from a waveform of the log data that has been called; retain afirst threshold related to acceleration in a gravity direction and asecond threshold related to acceleration in a traveling direction, setthe first threshold and the second threshold based on the discriminationresult; and configured to transmit the discrimination result, whereinthe at least one processor is configured to execute the instructions tooutput a discrimination result that it is erroneous activation, whenacceleration included in the log data has not exceeded the secondthreshold within a discrimination time, and update the first thresholdbased on a value of the acceleration in the traveling direction includedin the log data according to the discrimination result that it iserroneous activation.
 2. The discrimination device according to claim 1,wherein the at least one processor is configured to execute theinstructions to set, as the first threshold, a value obtained bymultiplying a maximum value of the acceleration in the travelingdirection included in the log data by a correction coefficient accordingto the discrimination result that it is erroneous activation.
 3. Thediscrimination device according to claim 1, wherein the at least oneprocessor is configured to execute the instructions to output thediscrimination result that it is stable walking when the accelerationincluded in the log data has exceeded the second threshold by aprescribed number of times or more within a discrimination time, andoutput the discrimination result that walking is stopped when theacceleration included in the log data has not exceeded the secondthreshold by the prescribed number of times or more within thediscrimination time.
 4. The discrimination device according to claim 1,wherein the at least one processor is configured to execute theinstructions to generate an instruction to decrease the first thresholdwhen the acceleration included in the log data has not exceeded thefirst threshold under a certain condition, and decrease the firstthreshold in response to the instruction to decrease the firstthreshold.
 5. The discrimination device according to claim 4, whereinthe at least one processor is configured to execute the instructions toset, in response to the instruction to decrease the first threshold, thefirst threshold to a value of the first threshold when it has beenpreviously distinguished that it is stable walking.
 6. Thediscrimination device according to claim 1, wherein the at least oneprocessor is configured to execute the instructions to acquire, at atime of initial setting, the log data of the sensor data acquired by thesensor installed in the shoe of the user performing stable walking, seta value obtained by multiplying a maximum value of the acceleration inthe traveling direction by a first coefficient as the first threshold,and set a value obtained by multiplying a second coefficient smallerthan the first coefficient by the maximum value of the acceleration inthe traveling direction as the second threshold.
 7. A walkingmeasurement system comprising: the discrimination device according toclaim 1; and a data acquisition device that is placed in a shoe, detectsacceleration and angular velocity, generates sensor data including thedetected acceleration and angular velocity, and transmits the generatedsensor data to the discrimination device.
 8. The walking measurementsystem according to claim 7, further comprising a walking measurementdevice that acquires the sensor data generated by the data acquisitiondevice and the discrimination result from the discrimination device, isactivated and stopped according to the discrimination result, andmeasures walking using the sensor data.
 9. A discrimination methodcomprising: acquiring sensor data including acceleration acquired by asensor placed in a shoe; storing log data of the acquired sensor data ina storage; calling the log data stored in the storage; distinguishing awalking state from a waveform of the called log data; setting a firstthreshold related to acceleration in a gravity direction and a secondthreshold related to acceleration in a traveling direction based on adiscrimination result of the walking state; outputting a discriminationresult that it is erroneous activation when acceleration included in thelog data has not exceeded the second threshold within a discriminationtime; and updating the first threshold based on a value of theacceleration in the traveling direction included in the log dataaccording to the discrimination result that it is erroneous activation.10. A non-transient program recording medium recording a program thatcauses a computer to execute processing comprising: acquiring sensordata including acceleration acquired by a sensor placed in a shoe;storing the log data of the acquired sensor data in a storage; callingthe log data stored in the storage; distinguishing a walking state froma waveform of the called log data; setting a first threshold related toacceleration in a gravity direction and a second threshold related toacceleration in a traveling direction based on a discrimination resultof the walking state; outputting a discrimination result that it iserroneous activation when acceleration included in the log data has notexceeded the second threshold within a discrimination time; and updatingthe first threshold based on a value of the acceleration in thetraveling direction included in the log data according to thediscrimination result that it is erroneous activation.